1. Field of the Invention
The present invention relates to a switching power supply.
2. Description of the Related Art
In order to generate a voltage higher than an input voltage or a voltage lower than the input voltage, a switching power supply is used. The switching power supply includes an output inductor, an output capacitor, a switching transistor and a control circuit used to control ON/OFF of the switching transistor.
In order to increase the efficiency of the switching power supply in a light load, sometimes an ON/OFF switching frequency of a switching element, that is, a switching frequency is reduced in the light load state. Therefore, a loss caused by an ON-state resistance of the switching element, a loss caused by a charging/discharging current of a gate capacitance of the switching element, and a loss of a rectifying element can be reduced.